Fluid-directing multiport rotary valve

ABSTRACT

A rotary valve for directing fluid streams which has a circular stationary head having at least one and desirably multiple primary ports for connection with fluid streams at least one secondary port. The stationary head includes a number of first circular concentric channels formed therein and at least one second concentric channel. The first and second channels are associated with the primary and secondary ports, respectively. A rotatable head is provided having radial chambers, each having a first and second port for connection between a first channel and a secondary port. The rotatable head rotates against the stationary head and channels in a fluid sealed manner. An indexable drive rotates the rotatable head to interconnect predetermined primary channels and secondary ports. The timing of rotation can be continuous or intermittent depending upon the associated process of the fluid streams.

FIELD OF THE INVENTION

This invention relates to a multiport rotary valve for directingmultiple fluid streams and, in particular to an improved rotary valvefor simultaneously directing a plurality of fluid streams into and outof a fluid-solid contacting apparatus employed for separating amulticomponent fluid mixture.

BACKGROUND OF THE INVENTION

Continuous fluid-solid contacting systems have been used to effect aseparation of a multicomponent fluid mixture into its components byemploying the different affinities of the solid towards individualcomponents of the fluid mixture. Typically, the fluid mixture in such aseparation is brought into contact with a bed of solid. As the fluidtravels further downstream in the bed of solid, it is enriched in thosecomponents that are only weakly retained by the solid. On the otherhand, the components that are strongly retained by the solid arerecovered by introducing into the solid bed an eluent stream to freethem from the solid. Generally, the effectiveness of the separation isincreased when the fluid and solid phases move countercurrently to eachother. However, an effective and easy-to-operate system in which thesolid phase is truly moved countercurrently to the fluid phase has notbeen developed. Instead, simulated moving bed contacting apparatuseshave been used in which a simulation of the movement of the solid phaseis carried out. In such a system, the points at which the feed andcluent streams are introduced into the solid bed and the points at whichthe enriched product streams are taken from the solid bed are movedsequentially and intermittently in the direction of the fluid flow. Asthe number of points of fluid introduction increases, the operationapproaches more closely the continuous countercurrent moving bed. At thesame time, the piping system becomes more complex, and the number ofvalves increases exponentially, resulting in a high cost. Therefore,effort has been expended to design a multiport rotary valve to replaceall the valves in a simulated moving bed wherein an external fluid isintroduced to various points in the solid bed by the rotation of someelements in the rotary valve so that a certain port communicates with anappropriate point in the solid bed. For example, U.S. Pat. No. 4,569,371issued to Dolejs et al. discloses a complicated unitary axial multipartrotary valve which comprises a three-section cylindrical hollowstationary body and a cylindrical rotating body which fits inside thestationary body. The connections through which feed, eluent, andproducts are conducted to and from the simulated moving bed are made tothe stationary body. Various channels are formed inside the rotatingbody and terminate in the circumferential surface of this rotating bodysuch that different connections may be rendered communicable by therotation of this rotating body. In order to ensure a successfuloperation, the bodies must be manufactured to a very high degree ofprecision. Even then, numerous sophisticated seals must be providedbetween the stationary and rotating bodies to prevent intermixing of thevarious fluid streams. As the rotating body becomes eroded with use, itcan be imagined that a significant effort must be expended to repair thevalve because of its complexity. Thus, such a valve incurs highinvestment and maintenance costs.

U.S. Pat. No. 5,676,826 issued to Rossiter and Riley disclosed afluid-solid contacting apparatus employing a rotary valve to conductfluid streams to and from the apparatus. The fluid-solid contactingapparatus of this invention comprises a plurality of chambers containinga solid, which chambers are installed on a rotating carousel. The valveof this invention comprises an annular stationary head and an annularrotating head. Conduits are formed inside the stationary head andterminated in two sets of openings on two surfaces of the stationaryhead. External fluids are supplied to the fluid-solid apparatus andproduct streams from the apparatus are taken away through the first setof openings on the circumferential surface of the stationary head. Fluidconduits from the entrance and exit ends of each chamber communicatewith still other sections of conduits precisely arranged in the rotatinghead. Through a synchronous rotation of the rotating head and thecarousel, the conduits in this head are aligned to the second set ofopenings on the stationary head, resulting in the appropriateconnections between external fluid conduits and selected chambers. Thenumber of conduits formed in the rotating head is very large becauseeach chamber is provided with two conduits: one to its entrance and oneto its exit end. Therefore, in order to ensure a perfect alignmentbetween certain of such a large number of conduits in the rotating headand the second set of openings in the stationary head, the manufacturingof such a valve requires a very high degree of precision, thus incurringa high cost. In addition, the operation of this rotary valve requiresthe synchronous rotation of both the rotating head of the valve and thecarousel of the chambers. As the scale of the operation and, thus, thesize of each of the chambers, increases the operation becomes expensiveor even impractical.

Therefore, it is an object of the present invention to provide animproved rotary valve for simultaneously directing a plurality of fluidstreams into and out of a fluid-solid contacting apparatus employed forseparating a multicomponent fluid mixture, which valve does not have thedisadvantages of the prior-art valves. It is a further object of thepresent invention to provide a rotary valve that has fewer moving partsand a simpler construction than prior-art rotary valves. Otheradvantages of the present invention will become apparent upon a perusalof the instant disclosure.

SUMMARY OF THE INVENTION

Generally, the present invention provides a multiport rotary valve whichhas a stationary circular head which has at least one primary port forconnection with a fluid stream and at least one secondary port. Inpractice, it is preferred to have a number of primary and secondaryports for connection with fluid separation equipment, for example.

The stationary head, which can comprises number of ports formed as acomponent assemble, includes one circular channel formed therein whichis associated with a primary port and at least one second concentriccircular channel associated with a secondary port or ports.

A rotatable head is provided having at least one radial chamber, theradial chamber includes first and second ports for connection with oneof at least one first channels and one of the second ports.

The valve includes an indexable drive for rotating the rotatable headbetween pre-selected primary and secondary ports.

In a presently preferred embodiment, a rotary valve is provided havingmultiple ports for connection with a plurality of externalfluid-carrying conduits to direct fluid streams contained in theseconduits, according to a pre-determined cycle, into and out of afluid-solid contacting apparatus comprising a plurality of separationzones for a separation of a multicomponent fluid mixture. The rotaryvalve permits the connection of a fluid-carrying conduit to at most oneother fluid-carrying conduit and prevents intermixing of fluidscontained in the different fluid-carrying conduits while such fluids areflowing through the apparatus. After a predetermined time, one of anytwo interconnected fluid-carrying conduits is replaced by a differentfluid-carrying conduit through a movement of an element of the rotaryvalve so that fluid is directed to or from a different position withinthe fluid-solid contacting apparatus. In the same manner, the rotaryvalve advances sequentially through its different positions or indicesin accordance with the previously determined cycle.

A preferred embodiment of the rotary valve comprises a plurality ofcooperative assemblies: a circular rotatable head having first andsecond opposed surfaces, and at least one stationary head assemblyhaving first and second opposed surfaces. The rotatable and stationaryhead assemblies have circular shapes of substantially equal diameters.The rotatable head is disposed adjacently to one stationary surface of astationary head assembly such that the centers of the assembliessubstantially coincide, and rotates about an axis of rotation that runsperpendicularly to the circular surfaces of the assemblies and throughtheir substantially coincident centers. The rotatable head assembly isurged against a stationary head assembly by a force that is supplied tothe surface of the rotatable head opposite to a stationary headassembly.

A plurality of concentric circular channels is formed in the secondstationary surface adjacent to the rotatable head. A plurality ofprimary connections is provided on the surface of a stationary headassembly opposite to the rotatable head assembly, through which primaryconnections fluid is conducted to or from the overall fluid-solidcontacting apparatus. Each primary connection communicates with acylindrical primary bore that runs through the thickness of thestationary head assembly on which these primary connections are disposedand terminates in one of the concentric circular channels of the samestationary head assembly. A plurality of secondary connections isuniformly spaced apart on a circle concentric with the circular channelsand attached to the same or another stationary head assembly, and formsan array of connections to intermediate points representing the end ofone and the beginning of another separation zone within the fluid-solidcontacting apparatus. Each secondary connection communicates with aseparate cylindrical secondary bore that runs through the thickness ofthe stationary head on which it is attached and that is in alignmentwith said secondary connection. The number of secondary connections isequal to the number of separation zones of the fluid-solid contactingapparatus so that each separation zone is connect to one secondaryconnection at an appropriate time.

A plurality of radial chambers are formed within the thickness of therotating head assembly so to allow for the communication between theprimary connections and each of the secondary connections. The number ofradial chambers are equal to the number of concentric circular channels.Each radial chamber connects the cylindrical secondary bore that is incommunication with a selected secondary connection to a cylindricalprimary bore that is in communication with one of the primaryconnections through one of the circular channels, thereby allowing fluidpresent at a primary connection to be conducted to a separation zone orallowing fluid from another separation zone to be conducted to anotherprimary connection. At a predetermined time, the rotating head assemblyrotates and advances to the next position or index so that fluid isconducted to and from the next separation zones in the sequence. In thismanner, each separation zone performs the separation of the fluidcomponents for a defined time and is subsequently treated by an eluentso that the separation capability of the solid is recovered for furtherseparation use for the same defined time.

The solid is often said to have been regenerated when its separationcapability has been recovered to such a degree that it becomes useableto effect the separation when it is contacted again with themulticomponent fluid mixture. The rotation of the rotating head assemblycan also be initiated when the concentration of a component of the fluidmixture coming from a separation zone reaches a predetermined level. Theseparation of the components of the fluid mixture is carried outcontinuously and indefinitely through the rotation of the rotating headassembly. Other advantages of the invention will become apparent from aperusal of the following detailed description of the presently preferredembodiment taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a multizone fluid-solid contactingapparatus for the separation of a multicomponent fluid mixture.

FIG. 2 is a sectional elevation of the first embodiment of the rotaryvalve of the present invention using a piston as the force-applyingmeans.

FIG. 3 is an enlarged section of the sealing mechanism between thepiston and the piston housing.

FIG. 4 is a sectional elevation of the first embodiment of the rotaryvalve of the present invention using a pressurized bladder as theforce-applying means.

FIG. 5 is a top plan of the stationary head assembly of the firstembodiment of the rotary valve of the present invention.

FIG. 6 is the top plan of the rotatable head of the first embodiment ofthe rotary valve of the present invention.

FIG. 7 is a sectional elevation of the second preferred embodiment ofthe rotary valve of the present invention including two stationary headassemblies and one rotating head assembly.

FIG. 8 is a top plan of the first stationary head assembly of the secondpreferred embodiment of the rotatable valve of the present invention.

FIG. 9 is a top plan of the second stationary head of the secondpreferred embodiment of the rotatable valve of the present invention.

FIG. 10 is a top plan of the rotatable head of the second preferredembodiment of the rotatable valve of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A presently preferred embodiment of the multiport rotary valve of thepresent invention is showed and described in conjunction with afluid-solid contacting apparatus wherein a multicomponent fluid mixtureis separated into its components by the different affinities of thecomponents of the fluid mixture towards the solid. In this embodiment,the components of the fluid mixture are retained in the solid more orless strongly depending on their affinities towards the solid. The lessstrongly retained components are carried in the fluid stream andconcentrated at a point downstream from the point at which the feedfluid mixture is introduced into the bed of solid. The term “raffinate”or “raffinate stream” is used herein to denote the stream containing theless strongly retained components. The more strongly retained componentsare concentrated on the solid and recovered by an eluent that reversiblyfrees them from the solid. The term “extract” or “extract stream” isused herein to denote the fluid stream containing the strongly retainedcomponents. In order for the separation process to be carried outcontinuously, the points at which the feed fluid mixture and the eluentare introduced into the bed of solid and those at which the raffinateand the extract are taken from the bed of solid must be movedperiodically along the bed in the direction of the fluid flow. Thus, thesolid may be viewed as being moved countercurrently to the fluid in asimulated fashion.

Referring to FIG. 1, the simulated moving bed of solid 100 that is usedin conjunction with the fluid-directing rotary valve of the presentinvention comprises a plurality of unit packed beds 1 through 8connected in series to, each other. The number of unit packed beds inthis figure serves only to illustrate the operation of the presentinvention, but any number of beds greater than or equal to four may beused. The exit end of one unit packed bed is connected to the entranceend of the next downstream unit packed bed to form an endlesscirculation loop. Each unit packed bed acts as a separation zone inwhich the fluid mixture is enriched in the less strongly retainedcomponents as the fluid mixture flows towards the exit end of the packedbed. At the same time, the more strongly retained components of thefluid mixture are progressively removed from the fluid and retained inthe solid. Alternatively, the separation zones may be contained in asingle vessel but separated from each other by any suitable separatingmeans such as a screen or a fluid distributing means that can effect asubstantially uniform distribution of the fluid over the cross sectionof the zone. In the latter configuration, the solid is contained in thevessel and the fluid distributing means serve as the demarcation linesbetween two adjacent separation zones. The feed fluid stream 20 isintroduced into the simulated moving bed 100 through the rotary valve200 of the present invention and through fluid conduit 5 a leading tothe entrance end of unit packed bed 5. The raffinate stream 21 is takenfrom the simulated moving bed 100 through the rotary valve 200 via fluidconduit 6 b leading from the exit end of unit packed bed 6. The eluentstream 22 is introduced into the simulated moving bed 100 through therotary valve 200 and through fluid conduit 1 a leading to the entranceend of unit packed bed 1. The extract stream 23 is taken from thesimulated moving bed 100 through the rotary valve 200 via fluid conduit2 b leading from the exit end of unit packed bed 2. Fluid moving means300, such as a pump, provides a continuous recirculation of fluidthrough the series of unit packed beds.

FIG. 2 shows a sectional elevation of the rotary valve of the presentinvention. The rotary valve 200 comprises two major assemblies: astationary head assembly 400 and a rotatable head 500; both are ofcircular shape having substantially equal diameter and each havingopposed surfaces. The stationary surface 401 of the stationary headassembly 400 is disposed adjacently to the rotating surface 501 of therotating head 500. The stationary head is preferably made of a polymericmaterial that is strongly resistant to abrasion and chemicallycompatible with the components of the fluid mixture; such polymericmaterial may be selected from the group consisting of high densitypolyethylene, ultrahigh density polyethylene, polypropylene,polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP),perfluoroalkoxyalkane (PFA), ethylene tetrafluoroethylene (ETFE),ethylene chlorotrifluoroethylene (ECTFE), polychlorotrifluoroethylene(PCTFE), polyvinyl chloride (PVC), polyvinylidenefluoride (PVDF),polyetheretherketone (PEEK), and derivatives thereof The stationary headassembly may also be made of a machinable metal that is compatible withthe components of the fluid mixture to be separated and may be selectedfrom the group consisting of brass; bronze; carbon steels; stainlesssteels; monel; nickel; titanium; zirconium; alloys of nickel, chromium,and iron; and alloys of nickel, iron, and molybdenum. The stationaryhead assembly may be optionally made of two plates attached or fastenedtogether, one slightly larger than the other so that there are providedpoints; for example, around the circumference of the larger plate; forattachment of the valve assembly to a fixed support. The rotating headassembly is preferably made of a machinable metal that is compatiblewith the components of the fluid mixture to be separated and may beselected from the group consisting of brass; bronze; carbon steels;stainless steels; monel; nickel; titanium; zirconium; alloys of nickel,chromium, and iron; and alloys of nickel, iron, and molybdenum. Therotating head assembly may also be made of a polymeric material that isstrongly resistant to abrasion an chemically compatible with thecomponents of the fluid mixture; such polymeric material may be selectedfrom the group consisting of high density polyethylene, ultrahighdensity polyethylene, polypropylene, polytetrafluoroethylene (PTFE),fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA),ethylene tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene(ECTFE), polychlorotrifluoroethylene (PCTFE), polyvinylchloride (PVC),polyvinylidenefluoride (PVDF), polyetheretherketone (PEEK), andderivatives thereof. The rotating head assembly is disposed adjacentlyto the stationary head assembly such that its rotating surface 501 iscooperatively matched with the stationary surface 401 of the stationaryhead assembly and the centers of the assemblies substantially coincide,and rotates about the axis of rotation 600 that runs perpendicularly tothe circular surfaces of the assemblies and through their substantiallycoincident centers. A piston housing 700 having a circular shape and atleast one flat surface 701 is disposed on the rotating head assemblyopposite to the stationary head assembly such that the flat surface 701of the piston housing is adjacent to the rotating head assembly. Anannular cylindrical depression 702 is formed into the piston housing andaway from the rotating head assembly 500. The piston housing 700 isfastened to the rotating head assembly 500 so that both rotate at thesame time. An annular piston 703 fits inside the annular cylindricaldepression 702 and is sealed against the piston housing 700 by a sealingmeans 704 such as a metal ring, an O-ring made of a polymeric material,or other compressible circular articles capable of providing a tightseal between the cylindrical surfaces of the piston and the pistonhousing. FIG. 3 shows an example of such a seal comprising a metal orplastic wear ring 710 in combination with a compressible ring 711 madeof a polymeric material. The piston 703 does not completely traverse thedepth of the annular cylindrical depression 702 so to leave a space 705between them. A compressed gas or hydraulic fluid is supplied into thespace 705 through connection 706 so that a force is applied on therotating head assembly 500 by which force the rotating head assembly 500is urged against the stationary head assembly 400 to provide a sealingaction between the rotating head assembly 500 and the stationary headassembly 400. A stationary support plate 800 is disposed adjacently toand fastened to the piston 703. The stationary support plate 800 is alsofastened to the stationary head assembly to provide stability to thewhole valve assembly. Other means for applying a force on the rotatinghead assembly may be used to perform the same function, in asubstantially similar manner, and to achieve a substantially similarresult. For example, in place of the piston, a pressurized bladder maybe provided to achieve the same objective. FIG. 4 shows this alternativeembodiment of the invention. A stationary bladder housing 750 having acircular shape and at least one flat surface 751 is disposed near therotating head assembly 500 and opposite to the stationary head assembly400. Thrust bearings 752 are disposed between the rotating head assembly500 and the bladder housing assembly 750 to provide a substantialstability to the rotating head assembly as it rotates. The bladderhousing 750 contains at least one annularly shaped bladder 753 thatresides in an annular channel 754 that is formed into the bladderhousing 750. A compressed gas or hydraulic fluid is supplied into thebladder 753 through connection 755 so that a force is applied on thethrust bearings 752 and the rotating head assembly 500 by which forcethe rotating head assembly 500 is urged against the stationary headassembly 400. A stationary support plate 800 is disposed adjacently toand fastened to the bladder housing 750. The stationary support plate800 is also fastened to the stationary head assembly 400 to providestability to the whole valve assembly. Still other embodiments offorce-applying means are possible. For example, the combination of thepiston housing 700 and the piston 703 may be replaced by a solid platewhich is disposed between the rotating head assembly 700 and thestationary support plate 800 and fastened to the stationary supportplate 800. A plurality of tightening fasteners are provided through thesupport plate 800 to apply a force on the rotating head assembly 500.These tightening fasteners are adjusted from time to time to keep asubstantially constant force on the rotating head assembly 500.

A plurality of concentric circular channels such as 411, 412, 413, and414 are formed into the stationary surface 401 of the stationary head.Thus, a fluid coming into a circular channel at any point in a circularchannel becomes available everywhere in this channel. The number of theconcentric circular channels is equal to the number of streams of fluidthat are to be conducted to and from outside the fluid-solid contactingapparatus. Thus, in the typical separation in which two input streams(one feed fluid mixture and one eluent) are conducted to and two outputstreams (one raffinate and one extract) are conducted away from thefluid-solid contacting apparatus, four concentric circular channels arerequired. In other situations where more than two products, more thanone feed, or more than one eluent is required, the number of concentricchannels will be more than four, but is always equal to the sum of thenumbers of input and output streams. In order to prevent leakage offluid between two adjacent circular channels or leakage of fluid fromthe valve, there is provided a circular draining groove 430 between twoadjacent channels or near the edges of the stationary head assembly. Adrain hole 431 is provided from each draining groove through thethickness of the stationary head assembly in order to carry away anyfluid leaking into the draining groove. In addition, leakage of fluidmay be further prevented by expandable circular seals disposed onstationary surface 401 of the stationary head assembly 400 on eitherside of each draining groove 430. Each of such expandable circular sealscomprises a spring disposed inside a housing made of a polymericmaterial and is located in a circular sealing groove formed on surface401. The opposing actions of the spring and the force-applying meanseliminates any leakage of fluid due to any unexpected gap that may existbetween the rotating head assembly and the stationary head assembly.

A plurality of primary connections such as 421, 422, 423, and 424 isprovided through the stationary surface 404 of the stationary headassembly opposite to the rotating head assembly, through whichconnections fluid is conducted to or from outside the fluid-solidcontacting apparatus. Thus, the number primary connections is equal tothe sum of the numbers of input fluid streams conducted to and of outputfluid streams away from the fluid-solid contacting apparatus and may begreater than four. Each of these primary connections communicates with acylindrical primary bore that runs through the thickness of thestationary head and terminates in one of the concentric circularchannels. An array of secondary connections 425 is uniformlyspaced-apart and arranged on a circle concentric with the channels andthrough the stationary surface 404 of the stationary head assembly. Theentrance end of each unit packed bed communicates with one suchsecondary connection via a separate fluid conduit. Thus, the number ofsecondary connections is equal to the number of unit packed beds. Eachsecondary connection 425 communicates with a cylindrical secondary bore435 that runs through the thickhess of the stationary head andterminates in an opening on stationary surface 401. FIG. 5 shows the topview of the stationary head assembly with the hidden locations of theprimary connections 421, 422, 423, and 424 and the secondary connections425. FIG. 5 also shows the concentric channels 411, 412, 413, and 414;each of which is in communication with a primary connection 421, 422,423, or 424. While the present preferred embodiment shows that the arrayof secondary connections 425 is arranged on a circle having anintermediate diameter, this circle may have a diameter greater than thatof the greatest circular channel or smaller than that of the smallestcircular channel, and the operation of the instant invention will not beaffected. Primary connection 421 serves, for example, to transport theraffinate stream away from the moving-bed fluid-solid contactingapparatus. Primary connection 422 serves, for example, as the point ofintroduction of the eluent fluid into the fluid-solid contactingapparatus. Primary connection 423 serves, for example, as the point ofintroduction of the feedstock fluid into the fluid-solid contactingapparatus. Primary connection 424 serves, for example, to transport theextract away from the fluid-solid contacting apparatus. FIG. 6 shows thetop view of the rotating head assembly of the first embodiment of therotary valve of the present invention. A plurality of Ushaped caverns iscut into the rotating head assembly. The number of such U-shaped cavernsis equal to the number of primary connections or the number ofconcentric channels. In this Figure, four such U-shaped caverns areshown representatively and are hidden from the top view. It isunderstood that more than four U-shaped caverns may be provided when thetotal number of fluid streams conducted to and away from the fluid-solidcontacting apparatus is greater than four. Each U-shaped cavern providesa means to communicate between one of the concentric channels in thestationary head assembly and a distinct secondary connection in the sameso that fluid present in a concentric channel is available to adifferent unit packed bed through the secondary connection, and viceversa. U-shaped cavern 451 connects the outermost circular channel 411to a first secondary connection 425 a. Through this cavern, circularchannel 411, and secondary connection 425 a; the raffinate stream fromthe unit packed bed connected with the secondary connection 425 a istaken away from the fluid-solid contacting apparatus. U-shaped cavern452 connects circular channel 412 to a second secondary connection 425b. Through this cavern, circular channel 412, and primary connection422; the eluent fluid is introduced into a second unit packed bed.U-shaped cavern 453 connects circular channel 413 to a third secondaryconnection 425 c. Through this cavern, circular channel 413, and primaryconnection 423; the feedstock fluid stream is introduced into thefluid-solid contacting apparatus. U-shaped cavern 454 connects circularchannel 414 to a fourth secondary connection 425 d. Through this cavern,circular channel 414, and primary connection 424; the extract stream isconducted away from the fluid-solid contacting apparatus. The relativepositions of the secondary connections 425 a, 425 b, 425 c, and 425 ddepend on the particular separation for which the moving-bed fluid-solidcontacting apparatus is used. For example, factors that influence thenumber of unit packed beds in series between the locations of any two ofthe secondary connections 425 a, 425 b, 425 c, and 425 d include, butare not limited to, the type of solid packing, the affinity of the solidtowards each component of the fluid mixture, the flow rate of the fluidmixture through the beds, the temperature of the fluid mixture, and thetype of eluent. The function of the rotary valve of the presentinvention is now further described in connection with the simulatedmoving-bed fluid-solid contacting apparatus of FIG. 1. A multicomponentfeedstock fluid mixture comprising at least one component that isrelatively weakly retained on the solid packing of the unit packed beds-and at least one other component that is relatively strongly retainedon the same solid is fed into the simulated moving-bed fluid-solidcontacting apparatus via primary connection 423, circular channel 413,U-shaped cavern 453, and secondary connection 425 c. In FIG. 1; forexample, outer connection 425 c is connected to the entrance of the unitpacked bed 5 via a fluid conduit 5 a. The fluid mixture flows throughthe series of unit packed beds 5 and 6 without traversing the rotaryvalve. As the fluid mixture flows through the unit packed beds, it isenriched in the components that are less strongly retained on the solid.This enriched stream is available in conduit 6 b connecting the exit endof unit packed bed 6 and the entrance end of unit packed bed 7. Part ofthis stream is taken out of the fluid-solid contacting apparatus as theraffinate stream via the rotary valve. This stream flows from conduit 6b to outer connection 425 a, through cavern 451, to circular channel411, and out of the apparatus via primary connection 421. An eluentstream is fed into the fluid-solid contacting apparatus at some unitpacked bed downstream to free the more strongly retained components ofthe fluid mixture from the solid. For example, in FIG. 1, the eluent isfed into the entrance of unit packed bed 1 via fluid conduit 1 a. Theeluent from outside the apparatus is fed into primary connection 422 onthe stationary head of the rotary valve, into circular channel 412,cavem 452, secondary connection 425 b, and to the entrance end of unitpacked bed 1 via fluid conduit 1 a. As the eluent flows through a seriesof unit packed beds, it becomes enriched with the more strongly retainedcomponents of the fluid mixture. A part of this stream is taken out ofthe fluid-solid contacting apparatus as the extract stream at a pointdownstream from the point of introduction of the eluent. For example, inFIG. 1, the eluent flows through unit packed beds 1 and 2 in series. Theextract stream is taken from fluid conduit to 2 b to secondaryconnection 425 d on the stationary head-of the rotary valve, throughcavern 454, into circular channel 414, and out of the fluid-solidcontacting apparatus via primary connection 424. After a predeterminedtime, or when the concentration of a component in the raffinate orextract stream reaches a predetermined level, the rotating head rotatesto the next position or index in the direction of the arrows in FIG. 4so that each of the U-shaped caverns 451, 452, 453, and 454 communicateswith the next unit packed bed in the series, respectively. In this way,the separation is carried out continuously and endlessly.

The rotating head assembly 500 of the rotary valve 200 of the presentinvention is driven by any suitable driving means 900, such as acombination of motor and gears or timing belts, a combination ofpneumatic reciprocating piston and ratchet arms, or other devices thatcan impart a rotation on the rotating head assembly. Finally, thestationary head, the rotating head, the pressure plate assemblies, andthe force-applying means are assembled together and attached to a fixedsupport.

FIG. 7 shows the cut-away view of a second preferred embodiment of thepresent invention. The rotary valve 1200 comprises three majorassemblies: a first stationary head assembly 1400, a second stationaryhead assembly 1450, and a rotating head assembly 1500; all are ofcircular shape. Each of the stationary head assembly has two opposedstationary surfaces. The rotating head assembly has two opposed rotatingsurfaces. The stationary head assemblies are preferably made of apolymeric material that is strongly resistant to abrasion and chemicallycompatible with the components of the fluid mixture; such polymericmaterial may be selected from-the group consisting of high densitypolyethylene, ultrahigh density polyethylene, polypropylene,polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP),perfluoroalkoxyalkane (PFA), ethylene tetrafluoroethylene (ETFE),ethylene chlorotrifluoroethylene (ECTFE), polychlorotrifluoroethylene(PCTFE), polyvinylchloride (PVC), polyvinylidenefluoride (PVDF),polyetheretherketone (PEEK), and derivatives thereof. The stationaryhead assemblies may also be made of a machinable metal that iscompatible with the components of the fluid mixture to be separated andmay be selected from the group consisting of brass; bronze; carbonsteels; stainless steels; monel; nickel; titanium; zirconium; alloys ofnickel, chromium, and iron; and alloys of nickel, iron, and molybdenum.The first stationary head assembly may be optionally made of two platesattached or fastened together, one slightly larger than the other sothat there are provided points; for example, around the circumference ofthe larger plate; for attachment of the valve assembly to a fixedsupport. The rotating head assembly is preferably made of a machinablemetal that is compatible with the components of the fluid mixture to beseparated and may be selected from the group consisting of brass;bronze; carbon steels; stainless steels; monel; nickel; titanium;zirconium; alloys of nickel, chromium, and iron; and alloys of nickel,iron, and molybdenum. The rotating head assembly may also be made of apolymeric material that is strongly resistant to abrasion and chemicallycompatible with the components of the fluid mixture; such polymericmaterial may be selected from the group consisting of high densitypolyethylene, ultrahigh density polyethylene, polypropylene,polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP),perfluoroalkoxyalkane (PFA), ethylene trifluoroethylene (ETFE), ethylenechlorotrifluoroethylene (ECTFE), polychlorotrifluoroethylene (PCTFE),ployvinylchloride (PVC), polyvinylidenefluoride (PVDF),polyetheretherketone (PEEK), and derivatives thereof. The rotating headassembly is disposed between the first and second stationary headassemblies such that its first circular rotating surface 1501 iscooperatively matched with the circular stationary surface 1401 of thefirst stationary head assembly, and its second circular rotating surface1502 is cooperatively matched with the circular stationary surface 1451of the second stationary head assembly, and such that the centers of theassemblies substantially coincide, and rotates about the axis ofrotation 1600 that runs perpendicularly to the circular surfaces of theassemblies and through their substantially coincident centers. A spaceor spaces 1702 are formed inside the bladder housing 1750, and one ormore pressurized bladders may be provided in the space or spaces 1702. Acompressed gas or hydraulic fluid is supplied into each bladder throughconnection 1755 so that a force is applied on the second stationary headassembly 1450 and the rotating head assembly 1500 by which force boththe second stationary head assembly 1450 and the rotating head assembly1500 are urged against the first stationary head assembly 1400. Thesecond stationary head assembly 1450 is fastened to the first stationaryhead assembly 1400 to provide stability to the whole valve assembly.Other embodiments of force-applying means as are described earlier inthe present disclosure are possible.

A plurality of concentric circular channels such as 1411, 1412, 1413,and 1414 are formed into the stationary surface 1401 of the stationaryhead. Thus, a fluid coming into a circular channel at any point in acircular channel becomes available everywhere in this channel. Thenumber of the concentric circular channels is equal to the number ofstreams of fluid that are to be conducted to and from outside thefluid-solid contacting apparatus. Thus, in the typical separation inwhich two input streams (one feed fluid mixture and one eluent) areconducted to and two output streams (one raffinate and one extract) areconducted away from the fluid-solid contacting apparatus, fourconcentric circular channels are required. In other situations wheremore than two products, more than one feed, or more than one eluent isrequired, the number of concentric channels will be more than four, butis always equal to the sum of the numbers of input and output streams.In order to prevent leakage of fluid between two adjacent circularchannels or leakage of fluid from the valve, there is provided acircular draining groove 1430 between two adjacent channels or near theedges of the stationary head assembly. A drain hole 1431 is providedfrom each draining groove through the thickness of the stationary headassembly in order to carry away any fluid leaking into the draininggroove. In addition, leakage of fluid may be further prevented byexpandable circular seals disposed on surface 1401 of the firststationary head assembly 1400 on either side of each draining groove1430. Each of such expandable circular seals comprises a spring disposedinside a housing made of a polymeric material and is located in acircular sealing groove formed on stationary surface 1401. The opposingactions of the spring and the force-applying means eliminates anyleakage of fluid due to any unexpected gap that may exist between therotating head assembly and the first stationary head assembly.

A plurality of primary connections such as 1421, 1422, 1423, and 1424 isprovided through the stationary surface 1404 of the first stationaryhead assembly opposite to the rotating head assembly, through whichconnections fluid is conducted to or from outside the fluid-solidcontacting apparatus. Thus, the number primary connections is equal tothe sum of the numbers of input fluid streams conducted to and of outputfluid streams away from the fluid-solid contacting apparatus and may begreater than four. Each of these primary connections communicates with acylindrical primary bore that runs through the thickness of the firststationary head and terminates in one of the concentric circularchannels. An array of secondary connections 1425 is uniformlyspaced-apart and arranged on a circle concentric with the circularchannels and through the stationary surface 1452 of the secondstationary head assembly opposite to the rotating head assembly. Theentrance end of each unit packed bed communicates with one suchsecondary connection via a separate fluid conduit. Thus, the number ofsecondary connections is equal to the number of unit packed beds. Eachsecondary connection 1425 communicates with a cylindrical secondary bore1435 that runs through the thickness of the second stationary head andterminates in an opening on flat surface 1451. FIG. 8 shows the top viewof the stationary head assembly with the hidden locations of the primaryconnections 1421, 1422, 1423, and 1424 and the concentric channels 1411,1412, 1413, and 1414; each of which concentric channels is incommunication with a primary connection 1421, 1422, 1423, or 1424. FIG.9 is the top view of the second stationary head assembly 1450 showingthe array of secondary connections 1425. The number of secondaryconnections is equal to the number of unit packed beds in thefluid-solid contacting apparatus. The number of secondary connectionsshown in FIG. 9 serves only to illustrate and to facilitate anunderstanding of, but in no way limits the present invention. Primaryconnection 1421 serves, for example, to transport the raffinate streamaway from the moving-bed fluid-solid contacting apparatus. Primaryconnection 1422 serves, for example, as the point of introduction of theeluent fluid into the fluid-solid contacting apparatus. Primaryconnection 1423 serves, for example, as the point of introduction of thefeedstock fluid into the fluid-solid contacting apparatus. Primaryconnection 1424 serves, for example, to transport the extract away fromthe fluid-solid contacting apparatus. FIG. 10 shows the bottom view ofthe rotating head assembly. A plurality of caverns is formed into therotating head assembly. The number of such caverns is equal to thenumber of primary connections or the number of concentric channels. InFIG. 10, four such caverns are shown representatively and are hiddenfrom the bottom view except for an opening from each cavern that servesas the communication with each concentric channel in the firststationary head assembly. It is understood that more than four cavernsmay be provided when the total number of fluid streams conducted to andaway from the fluid-solid contacting apparatus is greater than four.Each cavern provides a means to communicate between one of theconcentric channels in the stationary head assembly and a distinctsecondary connection on the second stationary head assembly so thatfluid present in a concentric channel is available to a different unitpacked bed through the secondary connection, and vice versa. Cavern 1451connects circular channel 1412 to a first secondary connection 1425 a.Through this cavern, circular channel 1412, and secondary connection1425 a; the raffinate stream from the unit packed bed connected with thesecondary connection 1425 a is taken away from the fluid-solidcontacting apparatus through primary connection 1421. Cavern 1452connects circular channel 1411 to a second secondary connection 1425 b.Through this cavern, circular channel 1411, and primary connection 1422;the eluent fluid is introduced into a second unit packed bed. In FIG.10, cavern 1452 is illustrated merely as a straight bore traversing thethickness of the rotating head assembly.

Cavern 1453 connects circular channel 1413 to a third secondaryconnection 1425 c. Through this cavern, circular channel 1413, andprimary connection 1423; the feedstock fluid stream is introduced intothe fluid-solid contacting apparatus. Cavern 1454 connects circularchannel 1414 to a fourth secondary connection 1425 d. Through thiscavern, circular channel 1414, and primary connection 1424; the extractstream is conducted away from the fluid-solid contacting apparatus. Therelative positions of the secondary connections 1425 a, 1425 b, 1425 c,and 1425 d depend on the particular separation for which the moving-bedfluid-solid contacting apparatus is used. For example, factors thatinfluence the number of unit packed beds in series between the locationsof any two of the secondary connections 1425 a, 1425 b, 1425 c, and 1425d include, but are not limited to, the type of solid packing, theaffinity of the solid towards each component of the fluid mixture, theflow rate of the fluid mixture through the beds, the temperature of thefluid mixture, and the type of eluent. The rotating head assembly 1500may be driven by any suitable driving means such as those enumeratedabove or their equivalents.

While the foregoing has described the preferred embodiments, and modesof operation of the present invention, it should be appreciated thatnumerous variations, changes, and equivalents may be made to theseembodiments, and modes of operations without departing from the scope ofthe present invention as defined by the following claims.

What is claimed:
 1. A multiport rotary valve for directing fluid streamscomprising: (a) a circular stationary head having at least one primaryport for connection with a fluid stream and at least one secondary port;at least one first circular channel formed in said stationary headassociated with a primary port and at least one concentric secondchannel formed in said stationary head associated with a secondary port;(b) a circular rotatable head having at least one radial chamber, saidradial chamber having first and second spaced apart ports for connectionbetween a first circular channel and a secondary port, said rotatablehead forming a fluid seal with said stationary head; and (c) anindexable drive for rotating said rotatable head to interconnectselected primary ports with selected secondary ports by use of saidradial chamber; wherein said fluid-solid contacting apparatus comprisesseparation zones arranged in series such that an exit end of oneseparation zone is connected to an entrance end of another separationzone next in a direction of fluid flow in said series and a fluid movingmeans to conduct said fluid continuously and endlessly within saidseries.
 2. A multiport rotary valve as set forth in claim 1 wherein asecond circular channel includes a plurality of associate secondaryports.
 3. A multiport rotary valve as set forth in claim 2 wherein saidstationary head includes a plurality of first circular channels, each ofsaid first circular channels having a primary port and wherein thenumber of radial chambers in said rotatable head is equal to the numberof first circular channels.
 4. A multiport rotary valve as set forth inclaim 1 including means for urging said stationary head and rotatablehead into sealing contact with each other.
 5. A multiport rotary valveas set forth in claim 1 wherein said stationary head comprises aplurality of second channels, each having an associated secondary port.6. A multiport rotary valve as set forth in claim 1 wherein at least oneof said stationary head is made of a polymeric material selected fromthe group consisting of high density polyethylene, ultrahigh densitypolyethylene, polypropylene, polytetrafluoroethylene (PTFE), fluorinatedethylene propylene (FEP), perfluoroalkoxyalkane (PFA), ethylenetetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene (ECTFE),polychlorotrifluoroethylene (PCTFE), polyvinylchloride (PVC),polyvinylidenefluoride (PVDF), polyetheretherketone (PEEK), andderivatives thereof or a metal selected from the group consisting ofbrass; bronze; carbon steels; stainless steels; monel; nickel; titanium;zirconium; alloys of nickel, chromium, and iron; and alloys of nickel,iron, and molybdenum.
 7. A multiport rotary valve as set forth in claim1 wherein said rotatable head is made of a polymeric material selectedfrom the group consisting of high density polyethylene, ultrahighdensity polyethylene, polypropylene, polytetrafluoroethylene (PTFE),fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA),ethylene tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene(ECTFE), polychlorotrifluoroethylene (PCTFE), polyvinylchloride (PVC),polyvinylidenefluoride (PVDF), polyetheretherketone (PEEK), andderivatives thereof or a metal selected from the group consisting ofbrass; bronze; carbon steels; stainless steels; monel; nickel; titanium;zirconium; alloys of nickel, chromium, and iron; and alloys of nickel,iron, and molybdenum.
 8. A multiport rotary valve for directing fluidstreams to and from a fluid-solid contacting apparatus, said multiportrotary valve comprising: (a) at least one stationary head having firstand second opposed stationary surfaces, said at least one stationaryhead comprising: (i) a plurality of primary connections being attachedto said first stationary surface and serving as points of introductionof a multicomponent feedstock fluid mixture and an eluent, and as pointsof removal of enriched products; (ii) a plurality of secondaryconnections being attached to said first stationary surface, and servingas communication means for directing fluid streams to and from afluid-solid contacting apparatus; (iii) a plurality of concentriccircular channels formed into said second stationary surface; and (iiii)a bore communicating with each of said primary and secondaryconnections; (b) a rotatable head having first and second opposedsurfaces, said first surface being disposed adjacently to said secondstationary surface such that centers of said stationary head and saidrotatable head substantially coincide, said rotatable head comprising:(i) a plurality of radial chambers being formed inside said rotatablehead and having openings on at least one of said surfaces, each of saidradial chambers connecting one of said circular channels to a selectedsecondary connection; (c) a force-applying means to apply a forceuniformly on said rotatable head to urge said rotatable head againstsaid stationary head; and (d) a drive means to effect a rotation of saidrotatable head about an axis of rotation which runs through saidsubstantially coincident centers of said stationary head and saidrotatable head; wherein said fluid-solid contacting apparatus comprisesseparation zones arranged in series such that an exit end of oneseparation zone is connected to an entrance end of another separationzone next in a direction of fluid flow in said series and a fluid movingmeans to conduct said fluid continuously and endlessly within saidseries.
 9. A multiport rotary valve for directing fluid streams to andfrom a fluid-solid contacting apparatus, said multiport rotary valvecomprising: (a) a first stationary head assembly having first and secondopposed stationary surfaces, said first stationary head assemblycomprising: (i) a plurality of primary connections being attached tosaid first stationary surface and serving as points of introduction of amulticomponent feedstock fluid mixture and an eluent, and as points ofremoval of enriched products; (ii) a plurality of concentric circularchannels formed into said second stationary surface; and (iii) aplurality of primary bores traversing a thickness of said firststationary head assembly, each of said primary bores communicating withone of said primary connections; (b) a second stationary head assemblycomprising: (i) a plurality of secondary connections being attachedthereto; and (ii) a plurality of secondary bores traversing a thicknessof said second stationary head assembly, each of said secondary borescommunicating with one of said secondary connections; (c) a rotatablehead being disposed between said first and second stationary headassemblies and having first and second opposed rotating surfaces, saidfirst rotating surface being disposed adjacently to said secondstationary surface of said first stationary head assembly such thatcenters of said first and second stationary head assemblies and saidrotatable head substantially coincide, said rotatable head comprising:(i) a plurality of radial chambers being formed inside said rotatinghead assembly and having one opening on each of said rotating surfaces,each of said radial chambers connecting one of said circular channels toa selected secondary connection; (d) a force-applying means to apply aforce uniformly on said second stationary head to urge said secondstationary head and said rotatable head against said first stationaryhead; and (e) a drive means to effect a rotation of said rotatable headabout an axis of rotation which runs through said substantiallycoincident centers of said first and second stationary head assembliesand said rotatable head assembly; wherein said fluid-solid contactingapparatus comprises separation zones arranged in series such that anexit end of one separation zone is connected to an entrance end ofanother separation zone next in a direction of fluid flow in said seriesand a fluid moving means to conduct said fluid continuously andendlessly within said series.
 10. A multiport rotary valve as set forthin claim 8 or 9 wherein the force-applying means comprises a pistonhousing being disposed adjacently to the second rotatable surface of therotatable head assembly such that centers of the piston housing, atleast one stationary head assembly, and the rotating head assemblysubstantially coincide; and a piston positioned in an annularcylindrical depression formed in the piston housing opposite to therotatable head; said piston and piston housing together defining a spacewithin said depression, which space is filled with a material selectedfrom the group consisting of compressed gases and hydraulic fluids, tourge the rotary head towards at least one stationary head.
 11. Amultiport rotary valve as set forth in claim 8 or 9 wherein theforce-applying means comprises a bladder housing which is disposed onone side of the rotating head and opposite to one stationary head suchthat centers of said bladder housing, said stationary head, and saidrotatable head substantially coincide; a bladder positioned in anannular cylindrical depression which is formed in said bladder housingopposite to said rotatable head; and thrust bearings disposed betweensaid bladder housing and said rotating head assembly; said bladder beingfilled with a material selected from the group consisting of compressedgases and hydraulic fluids to urge said rotatable head towards at leastone stationary head.
 12. A multiport rotary valve as set forth in claim8 or 9 wherein the force-applying means comprises a solid plate which isdisposed adjacently to a second surface of said rotatable head, and astationary pressure plate which is disposed adjacently to said solidplate and opposite to said rotatable head; said solid plate and saidstationary pressure plate being fastened together by a plurality oftightening fasteners which are adjusted from time to time to keep asubstantially constant force on said rotating head assembly.
 13. Amultiport rotary valve as set forth in claim 1, 8 or 9 wherein rotationof said drive is initiated by an expiration of a predetermined time. 14.A multiport rotary valve as set forth in claim 1, 6 or 7 wherein saidseparation zones are arranged distinctly in series in a common vesseland said fluid moving means conducts said fluid from one end of saidvessel to another end of said vessel.
 15. A multiport rotary valve asset forth in claim 1, 8, or 9 further including a plurality of draininggrooves, at least one of said grooves being formed between two circularchannels to prevent a leakage of fluid between said circular channelsand at least one other of said draining grooves being formed between anoutermost circular channel and an edge of said stationary head.
 16. Amultiport rotary valve as set forth in claim 15 further including adrain hole which runs from each of said draining grooves to a firststationary surface of said stationary head assembly.
 17. A multiportrotary valve as set forth in claim 16 further including a plurality ofexpandable circular seals, at least one of said seals being disposed ina sealing groove formed adjacent to one of said draining grooves in saidstationary head to prevent a leakage of fluid between said circularchannels and at least one other of said expandable circular seals beinglocated in another sealing groove formed between an outermost circularchannel and an edge of said stationary head.
 18. A multiport rotaryvalve for directing fluid streams comprising: (a) a first head havingopposed surfaces, comprising at least two first ports located on thesame surface for connection with an external fluid stream, and having aseparate channel associated with each first port leading to a secondport corresponding to the first port and located on the surface oppositethe first port; (b) a rotatable second head having at least two thirdports each in communication with a separate second port and channel andlocated on a surface in contact with the surface of the first headcontaining the second ports, said third ports leading to an inlet oroutlet of a chamber containing a fluid-solid contacting medium so as toform a fluid seal between the chamber and an external fluid stream; and(c) a drive for rotating at least one of said heads to interconnect aselected external fluid stream with a selected chamber for apredetermined period of time before permitting interconnection of saidexternal fluid stream with a different chamber; (d) the ports beingconfigurable to permit said external fluid streams to be delivered tomultiple or successive chambers in series or in parallel or to bypass aselected chamber simultaneous with the delivery of other external fluidstreams.
 19. The multiport rotary valve of claim 18 wherein the firsthead is stationary.
 20. The multiport rotary valve of claim 18 whereinthe first head is stationary relative to the second head during theperiod of interconnection of each external fluid stream with a chamber.21. A multiport rotary valve for directing fluid streams to and from afluid-solid contacting apparatus, said multiport rotary valvecomprising: (a) a first stationary head assembly having first and secondstationary surfaces, said first stationary head assembly comprising: (i)a plurality of primary connections being attached to said firststationary surface and serving as points of introduction of amulticomponent feedstock fluid mixture or an eluent, or as points ofremoval of enriched products; (ii) a plurality of concentric circularchannels formed into said second stationary surface; and (iii) aplurality of primary bores traversing a thickness of said firststationary head assembly, each of said primary bores communicating withone of said primary connections; (b) a second stationary head assemblyhaving third and fourth stationary surfaces, said second stationary headassembly comprising: (i) a plurality of secondary connections beingattached to said third stationary surface and serving as points ofintroduction of a multicomponent feedstock fluid mixture or an eluent,or as points of removal of enriched products; (ii) a plurality ofconcentric circular channels formed into said fourth stationary surface;and (iii) a plurality of secondary bores traversing a thickness of saidsecond stationary head assembly, each of said secondary borescommunicating with one of said secondary connections; (c) a rotatablehead being disposed between said first and second stationary headassemblies and having rotating surfaces, two of said rotating surfacesbeing disposed adjacently to said first and second stationary headassemblies such that centers of said first and second stationary headassemblies and said rotatable head substantially coincide, saidrotatable head comprising: (i) a plurality of radial chambers beingformed inside said rotating head assembly with two openings on differentrotating surfaces, each of said radial chambers connecting one of saidcircular channels to said fluid-solid contacting apparatus; (e) a drivemeans to effect a rotation of said rotatable head about an axis ofrotation which runs through said substantially coincident centers ofsaid first and second stationary head assemblies and said rotatable headassembly; wherein said fluid-solid contacting apparatus comprisesseparation zones arranged such that an exit end of one separation zoneis connected to an entrance end of another separation zone next in adirection of fluid flow and a fluid moving means to conduct fluidcontinuously and endlessly within said apparatus.